/*
 * Copyright (c) 2014 ResiliNets, ITTC, University of Kansas
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Truc Anh N Nguyen <trucanh524@gmail.com>
 * Modified by:   Pasquale Imputato <p.imputato@gmail.com>
 *
 */

#include "ns3/codel-queue-disc.h"
#include "ns3/double.h"
#include "ns3/log.h"
#include "ns3/packet.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/test.h"
#include "ns3/uinteger.h"

using namespace ns3;

// The following code borrowed from Linux codel.h, for unit testing
#define REC_INV_SQRT_BITS_ns3 (8 * sizeof(uint16_t))
/* or sizeof_in_bits(rec_inv_sqrt) */
/* needed shift to get a Q0.32 number from rec_inv_sqrt */
#define REC_INV_SQRT_SHIFT_ns3 (32 - REC_INV_SQRT_BITS_ns3)

static uint16_t
_codel_Newton_step(uint16_t rec_inv_sqrt, uint32_t count)
{
    uint32_t invsqrt = ((uint32_t)rec_inv_sqrt) << REC_INV_SQRT_SHIFT_ns3;
    uint32_t invsqrt2 = ((uint64_t)invsqrt * invsqrt) >> 32;
    uint64_t val = (3LL << 32) - ((uint64_t)count * invsqrt2);

    val >>= 2; /* avoid overflow in following multiply */
    val = (val * invsqrt) >> (32 - 2 + 1);
    return static_cast<uint16_t>(val >> REC_INV_SQRT_SHIFT_ns3);
}

static uint32_t
_reciprocal_scale(uint32_t val, uint32_t ep_ro)
{
    return (uint32_t)(((uint64_t)val * ep_ro) >> 32);
}

// End Linux borrow

/**
 * \ingroup traffic-control-test
 *
 * \brief Codel Queue Disc Test Item
 */
class CodelQueueDiscTestItem : public QueueDiscItem
{
  public:
    /**
     * Constructor
     *
     * \param p packet
     * \param addr address
     * \param ecnCapable ECN capable
     */
    CodelQueueDiscTestItem(Ptr<Packet> p, const Address& addr, bool ecnCapable);
    ~CodelQueueDiscTestItem() override;

    // Delete default constructor, copy constructor and assignment operator to avoid misuse
    CodelQueueDiscTestItem() = delete;
    CodelQueueDiscTestItem(const CodelQueueDiscTestItem&) = delete;
    CodelQueueDiscTestItem& operator=(const CodelQueueDiscTestItem&) = delete;

    void AddHeader() override;
    bool Mark() override;

  private:
    bool m_ecnCapablePacket; ///< ECN capable packet?
};

CodelQueueDiscTestItem::CodelQueueDiscTestItem(Ptr<Packet> p, const Address& addr, bool ecnCapable)
    : QueueDiscItem(p, addr, 0),
      m_ecnCapablePacket(ecnCapable)
{
}

CodelQueueDiscTestItem::~CodelQueueDiscTestItem()
{
}

void
CodelQueueDiscTestItem::AddHeader()
{
}

bool
CodelQueueDiscTestItem::Mark()
{
    return m_ecnCapablePacket;
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 1: simple enqueue/dequeue with no drops
 */
class CoDelQueueDiscBasicEnqueueDequeue : public TestCase
{
  public:
    /**
     * Constructor
     *
     * \param mode the mode
     */
    CoDelQueueDiscBasicEnqueueDequeue(QueueSizeUnit mode);
    void DoRun() override;

  private:
    QueueSizeUnit m_mode; ///< mode
};

CoDelQueueDiscBasicEnqueueDequeue::CoDelQueueDiscBasicEnqueueDequeue(QueueSizeUnit mode)
    : TestCase("Basic enqueue and dequeue operations, and attribute setting")
{
    m_mode = mode;
}

void
CoDelQueueDiscBasicEnqueueDequeue::DoRun()
{
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();

    uint32_t pktSize = 1000;
    uint32_t modeSize = 0;

    Address dest;

    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("MinBytes", UintegerValue(pktSize)),
                          true,
                          "Verify that we can actually set the attribute MinBytes");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("Interval", StringValue("50ms")),
                          true,
                          "Verify that we can actually set the attribute Interval");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("Target", StringValue("4ms")),
                          true,
                          "Verify that we can actually set the attribute Target");

    if (m_mode == QueueSizeUnit::BYTES)
    {
        modeSize = pktSize;
    }
    else if (m_mode == QueueSizeUnit::PACKETS)
    {
        modeSize = 1;
    }
    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 1500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    queue->Initialize();

    Ptr<Packet> p1;
    Ptr<Packet> p2;
    Ptr<Packet> p3;
    Ptr<Packet> p4;
    Ptr<Packet> p5;
    Ptr<Packet> p6;
    p1 = Create<Packet>(pktSize);
    p2 = Create<Packet>(pktSize);
    p3 = Create<Packet>(pktSize);
    p4 = Create<Packet>(pktSize);
    p5 = Create<Packet>(pktSize);
    p6 = Create<Packet>(pktSize);

    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          0 * modeSize,
                          "There should be no packets in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p1, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          1 * modeSize,
                          "There should be one packet in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p2, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          2 * modeSize,
                          "There should be two packets in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p3, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          3 * modeSize,
                          "There should be three packets in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p4, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          4 * modeSize,
                          "There should be four packets in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p5, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          5 * modeSize,
                          "There should be five packets in queue");
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p6, dest, false));
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          6 * modeSize,
                          "There should be six packets in queue");

    NS_TEST_ASSERT_MSG_EQ(queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::OVERLIMIT_DROP),
                          0,
                          "There should be no packets being dropped due to full queue");

    Ptr<QueueDiscItem> item;

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the first packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          5 * modeSize,
                          "There should be five packets in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(), p1->GetUid(), "was this the first packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the second packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          4 * modeSize,
                          "There should be four packets in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(),
                          p2->GetUid(),
                          "Was this the second packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the third packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          3 * modeSize,
                          "There should be three packets in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(), p3->GetUid(), "Was this the third packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the forth packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          2 * modeSize,
                          "There should be two packets in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(),
                          p4->GetUid(),
                          "Was this the fourth packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the fifth packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          1 * modeSize,
                          "There should be one packet in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(), p5->GetUid(), "Was this the fifth packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_NE(item, nullptr, "I want to remove the last packet");
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          0 * modeSize,
                          "There should be zero packet in queue");
    NS_TEST_ASSERT_MSG_EQ(item->GetPacket()->GetUid(), p6->GetUid(), "Was this the sixth packet ?");

    item = queue->Dequeue();
    NS_TEST_ASSERT_MSG_EQ(item, nullptr, "There are really no packets in queue");

    NS_TEST_ASSERT_MSG_EQ(
        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP),
        0,
        "There should be no packet drops according to CoDel algorithm");
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 2: enqueue with drops due to queue overflow
 */
class CoDelQueueDiscBasicOverflow : public TestCase
{
  public:
    /**
     * Constructor
     *
     * \param mode the mode
     */
    CoDelQueueDiscBasicOverflow(QueueSizeUnit mode);
    void DoRun() override;

  private:
    /**
     * Enqueue function
     * \param queue the queue disc
     * \param size the size
     * \param nPkt the number of packets
     */
    void Enqueue(Ptr<CoDelQueueDisc> queue, uint32_t size, uint32_t nPkt);
    QueueSizeUnit m_mode; ///< mode
};

CoDelQueueDiscBasicOverflow::CoDelQueueDiscBasicOverflow(QueueSizeUnit mode)
    : TestCase("Basic overflow behavior")
{
    m_mode = mode;
}

void
CoDelQueueDiscBasicOverflow::DoRun()
{
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();
    uint32_t pktSize = 1000;
    uint32_t modeSize = 0;

    Address dest;

    if (m_mode == QueueSizeUnit::BYTES)
    {
        modeSize = pktSize;
    }
    else if (m_mode == QueueSizeUnit::PACKETS)
    {
        modeSize = 1;
    }

    Ptr<Packet> p1;
    Ptr<Packet> p2;
    Ptr<Packet> p3;
    p1 = Create<Packet>(pktSize);
    p2 = Create<Packet>(pktSize);
    p3 = Create<Packet>(pktSize);

    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("MinBytes", UintegerValue(pktSize)),
                          true,
                          "Verify that we can actually set the attribute MinBytes");

    queue->Initialize();

    Enqueue(queue, pktSize, 500);
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p1, dest, false));
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p2, dest, false));
    queue->Enqueue(Create<CodelQueueDiscTestItem>(p3, dest, false));

    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          500 * modeSize,
                          "There should be 500 packets in queue");
    NS_TEST_ASSERT_MSG_EQ(queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::OVERLIMIT_DROP),
                          3,
                          "There should be three packets being dropped due to full queue");
}

void
CoDelQueueDiscBasicOverflow::Enqueue(Ptr<CoDelQueueDisc> queue, uint32_t size, uint32_t nPkt)
{
    Address dest;
    for (uint32_t i = 0; i < nPkt; i++)
    {
        queue->Enqueue(Create<CodelQueueDiscTestItem>(Create<Packet>(size), dest, false));
    }
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 3: NewtonStep unit test - test against explicit port of Linux implementation
 */
class CoDelQueueDiscNewtonStepTest : public TestCase
{
  public:
    CoDelQueueDiscNewtonStepTest();
    void DoRun() override;
};

CoDelQueueDiscNewtonStepTest::CoDelQueueDiscNewtonStepTest()
    : TestCase("NewtonStep arithmetic unit test")
{
}

void
CoDelQueueDiscNewtonStepTest::DoRun()
{
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();

    // Spot check a few points in the expected operational range of
    // CoDelQueueDisc's m_count and m_recInvSqrt variables
    uint16_t result;
    for (uint16_t recInvSqrt = 0xff; recInvSqrt > 0; recInvSqrt /= 2)
    {
        for (uint32_t count = 1; count < 0xff; count *= 2)
        {
            result = queue->NewtonStep(recInvSqrt, count);
            // Test that ns-3 value is exactly the same as the Linux value
            NS_TEST_ASSERT_MSG_EQ(_codel_Newton_step(recInvSqrt, count),
                                  result,
                                  "ns-3 NewtonStep() fails to match Linux equivalent");
        }
    }
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 4: ControlLaw unit test - test against explicit port of Linux implementation
 */
class CoDelQueueDiscControlLawTest : public TestCase
{
  public:
    CoDelQueueDiscControlLawTest();
    void DoRun() override;
    /**
     * Codel control law function
     * \param t
     * \param interval
     * \param recInvSqrt
     * \returns the codel control law
     */
    uint32_t _codel_control_law(uint32_t t, uint32_t interval, uint32_t recInvSqrt);
};

CoDelQueueDiscControlLawTest::CoDelQueueDiscControlLawTest()
    : TestCase("ControlLaw arithmetic unit test")
{
}

// The following code borrowed from Linux codel.h,
// except the addition of queue parameter
uint32_t
CoDelQueueDiscControlLawTest::_codel_control_law(uint32_t t, uint32_t interval, uint32_t recInvSqrt)
{
    return t + _reciprocal_scale(interval, recInvSqrt << REC_INV_SQRT_SHIFT_ns3);
}

// End Linux borrow

void
CoDelQueueDiscControlLawTest::DoRun()
{
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();

    // Check a few points within the operational range of ControlLaw
    uint32_t interval = queue->Time2CoDel(MilliSeconds(100));

    uint32_t codelTimeVal;
    for (Time timeVal = Seconds(0); timeVal <= Seconds(20); timeVal += MilliSeconds(100))
    {
        for (uint16_t recInvSqrt = 0xff; recInvSqrt > 0; recInvSqrt /= 2)
        {
            codelTimeVal = queue->Time2CoDel(timeVal);
            uint32_t ns3Result = queue->ControlLaw(codelTimeVal, interval, recInvSqrt);
            uint32_t linuxResult = _codel_control_law(codelTimeVal, interval, recInvSqrt);
            NS_TEST_ASSERT_MSG_EQ(ns3Result,
                                  linuxResult,
                                  "Linux result for ControlLaw should equal ns-3 result");
        }
    }
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 5: enqueue/dequeue with drops according to CoDel algorithm
 */
class CoDelQueueDiscBasicDrop : public TestCase
{
  public:
    /**
     * Constructor
     *
     * \param mode the mode
     */
    CoDelQueueDiscBasicDrop(QueueSizeUnit mode);
    void DoRun() override;

  private:
    /**
     * Enqueue function
     * \param queue the queue disc
     * \param size the size
     * \param nPkt the number of packets
     */
    void Enqueue(Ptr<CoDelQueueDisc> queue, uint32_t size, uint32_t nPkt);
    /** Dequeue function
     * \param queue the queue disc
     * \param modeSize the mode size
     */
    void Dequeue(Ptr<CoDelQueueDisc> queue, uint32_t modeSize);
    /**
     * Drop next tracer function
     * \param oldVal the old value
     * \param newVal the new value
     */
    void DropNextTracer(uint32_t oldVal, uint32_t newVal);
    QueueSizeUnit m_mode;     ///< mode
    uint32_t m_dropNextCount; ///< count the number of times m_dropNext is recalculated
};

CoDelQueueDiscBasicDrop::CoDelQueueDiscBasicDrop(QueueSizeUnit mode)
    : TestCase("Basic drop operations")
{
    m_mode = mode;
    m_dropNextCount = 0;
}

void
CoDelQueueDiscBasicDrop::DropNextTracer(uint32_t /* oldVal */, uint32_t /* newVal */)
{
    m_dropNextCount++;
}

void
CoDelQueueDiscBasicDrop::DoRun()
{
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();
    uint32_t pktSize = 1000;
    uint32_t modeSize = 0;

    if (m_mode == QueueSizeUnit::BYTES)
    {
        modeSize = pktSize;
    }
    else if (m_mode == QueueSizeUnit::PACKETS)
    {
        modeSize = 1;
    }

    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");

    queue->Initialize();

    Enqueue(queue, pktSize, 20);
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          20 * modeSize,
                          "There should be 20 packets in queue.");

    // Although the first dequeue occurs with a sojourn time above target
    // the dequeue should be successful in this interval
    Time waitUntilFirstDequeue = 2 * queue->GetTarget();
    Simulator::Schedule(waitUntilFirstDequeue,
                        &CoDelQueueDiscBasicDrop::Dequeue,
                        this,
                        queue,
                        modeSize);

    // This dequeue should cause a drop
    Time waitUntilSecondDequeue = waitUntilFirstDequeue + 2 * queue->GetInterval();
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicDrop::Dequeue,
                        this,
                        queue,
                        modeSize);

    // Although we are in dropping state, it's not time for next drop
    // the dequeue should not cause a drop
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicDrop::Dequeue,
                        this,
                        queue,
                        modeSize);

    // In dropping time and it's time for next drop
    // the dequeue should cause additional packet drops
    Simulator::Schedule(waitUntilSecondDequeue * 2,
                        &CoDelQueueDiscBasicDrop::Dequeue,
                        this,
                        queue,
                        modeSize);

    Simulator::Run();
    Simulator::Destroy();
}

void
CoDelQueueDiscBasicDrop::Enqueue(Ptr<CoDelQueueDisc> queue, uint32_t size, uint32_t nPkt)
{
    Address dest;
    for (uint32_t i = 0; i < nPkt; i++)
    {
        queue->Enqueue(Create<CodelQueueDiscTestItem>(Create<Packet>(size), dest, false));
    }
}

void
CoDelQueueDiscBasicDrop::Dequeue(Ptr<CoDelQueueDisc> queue, uint32_t modeSize)
{
    uint32_t initialDropCount =
        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
    uint32_t initialQSize = queue->GetCurrentSize().GetValue();
    uint32_t initialDropNext = queue->GetDropNext();
    Time currentTime = Simulator::Now();
    uint32_t currentDropCount = 0;

    if (initialDropCount > 0 && currentTime.GetMicroSeconds() >= initialDropNext)
    {
        queue->TraceConnectWithoutContext(
            "DropNext",
            MakeCallback(&CoDelQueueDiscBasicDrop::DropNextTracer, this));
    }

    if (initialQSize != 0)
    {
        Ptr<QueueDiscItem> item = queue->Dequeue();
        if (initialDropCount == 0 && currentTime > queue->GetTarget())
        {
            if (currentTime < queue->GetInterval())
            {
                currentDropCount =
                    queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                NS_TEST_EXPECT_MSG_EQ(currentDropCount,
                                      0,
                                      "We are not in dropping state."
                                      "Sojourn time has just gone above target from below."
                                      "Hence, there should be no packet drops");
                NS_TEST_EXPECT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                      initialQSize - modeSize,
                                      "There should be 1 packet dequeued.");
            }
            else if (currentTime >= queue->GetInterval())
            {
                currentDropCount =
                    queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                NS_TEST_EXPECT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                      initialQSize - 2 * modeSize,
                                      "Sojourn time has been above target for at least interval."
                                      "We enter the dropping state, perform initial packet drop, "
                                      "and dequeue the next."
                                      "So there should be 2 more packets dequeued.");
                NS_TEST_EXPECT_MSG_EQ(currentDropCount, 1, "There should be 1 packet drop");
            }
        }
        else if (initialDropCount > 0)
        { // In dropping state
            if (currentTime.GetMicroSeconds() < initialDropNext)
            {
                currentDropCount =
                    queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                NS_TEST_EXPECT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                      initialQSize - modeSize,
                                      "We are in dropping state."
                                      "Sojourn is still above target."
                                      "However, it's not time for next drop."
                                      "So there should be only 1 more packet dequeued");

                NS_TEST_EXPECT_MSG_EQ(
                    currentDropCount,
                    1,
                    "There should still be only 1 packet drop from the last dequeue");
            }
            else if (currentTime.GetMicroSeconds() >= initialDropNext)
            {
                currentDropCount =
                    queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                NS_TEST_EXPECT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                      initialQSize - (m_dropNextCount + 1) * modeSize,
                                      "We are in dropping state."
                                      "It's time for next drop."
                                      "The number of packets dequeued equals to the number of "
                                      "times m_dropNext is updated plus initial dequeue");
                NS_TEST_EXPECT_MSG_EQ(currentDropCount,
                                      1 + m_dropNextCount,
                                      "The number of drops equals to the number of times "
                                      "m_dropNext is updated plus 1 from last dequeue");
            }
        }
    }
}

/**
 * \ingroup traffic-control-test
 *
 * \brief Test 6: enqueue/dequeue with marks according to CoDel algorithm
 */
class CoDelQueueDiscBasicMark : public TestCase
{
  public:
    /**
     * Constructor
     *
     * \param mode the mode
     */
    CoDelQueueDiscBasicMark(QueueSizeUnit mode);
    void DoRun() override;

  private:
    /**
     * Enqueue function
     * \param queue the queue disc
     * \param size the size
     * \param nPkt the number of packets
     * \param ecnCapable ECN capable traffic
     */
    void Enqueue(Ptr<CoDelQueueDisc> queue, uint32_t size, uint32_t nPkt, bool ecnCapable);
    /** Dequeue function
     * \param queue the queue disc
     * \param modeSize the mode size
     * \param testCase the test case number
     */
    void Dequeue(Ptr<CoDelQueueDisc> queue, uint32_t modeSize, uint32_t testCase);
    /**
     * Drop next tracer function
     * \param oldVal the old value
     * \param newVal the new value
     */
    void DropNextTracer(uint32_t oldVal, uint32_t newVal);
    QueueSizeUnit m_mode;             ///< mode
    uint32_t m_dropNextCount;         ///< count the number of times m_dropNext is recalculated
    uint32_t nPacketsBeforeFirstDrop; ///< Number of packets in the queue before first drop
    uint32_t nPacketsBeforeFirstMark; ///< Number of packets in the queue before first mark
};

CoDelQueueDiscBasicMark::CoDelQueueDiscBasicMark(QueueSizeUnit mode)
    : TestCase("Basic mark operations")
{
    m_mode = mode;
    m_dropNextCount = 0;
}

void
CoDelQueueDiscBasicMark::DropNextTracer(uint32_t /* oldVal */, uint32_t /* newVal */)
{
    m_dropNextCount++;
}

void
CoDelQueueDiscBasicMark::DoRun()
{
    // Test is divided into 4 sub test cases:
    // 1) Packets are not ECN capable.
    // 2) Packets are ECN capable but marking due to exceeding CE threshold disabled
    // 3) Some packets are ECN capable, with CE threshold set to 2ms.
    // 4) Packets are ECN capable and CE threshold set to 2ms

    // Test case 1
    Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc>();
    uint32_t pktSize = 1000;
    uint32_t modeSize = 0;
    nPacketsBeforeFirstDrop = 0;
    nPacketsBeforeFirstMark = 0;

    if (m_mode == QueueSizeUnit::BYTES)
    {
        modeSize = pktSize;
    }
    else if (m_mode == QueueSizeUnit::PACKETS)
    {
        modeSize = 1;
    }

    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("UseEcn", BooleanValue(true)),
                          true,
                          "Verify that we can actually set the attribute UseEcn");

    queue->Initialize();

    // Not-ECT traffic to induce packet drop
    Enqueue(queue, pktSize, 20, false);
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          20 * modeSize,
                          "There should be 20 packets in queue.");

    // Although the first dequeue occurs with a sojourn time above target
    // there should not be any dropped packets in this interval
    Time waitUntilFirstDequeue = 2 * queue->GetTarget();
    Simulator::Schedule(waitUntilFirstDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        1);

    // This dequeue should cause a packet to be dropped
    Time waitUntilSecondDequeue = waitUntilFirstDequeue + 2 * queue->GetInterval();
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        1);

    Simulator::Run();
    Simulator::Destroy();

    // Test case 2, queue with ECN capable traffic for marking of packets instead of dropping
    queue = CreateObject<CoDelQueueDisc>();
    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("UseEcn", BooleanValue(true)),
                          true,
                          "Verify that we can actually set the attribute UseEcn");

    queue->Initialize();

    // ECN capable traffic to induce packets to be marked
    Enqueue(queue, pktSize, 20, true);
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          20 * modeSize,
                          "There should be 20 packets in queue.");

    // Although the first dequeue occurs with a sojourn time above target
    // there should not be any target exceeded marked packets in this interval
    Simulator::Schedule(waitUntilFirstDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        2);

    // This dequeue should cause a packet to be marked
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        2);

    // Although we are in dropping state, it's not time for next packet to be target exceeded marked
    // the dequeue should not cause a packet to be target exceeded marked
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        2);

    // In dropping time and it's time for next packet to be target exceeded marked
    // the dequeue should cause additional packet to be target exceeded marked
    Simulator::Schedule(waitUntilSecondDequeue * 2,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        2);

    Simulator::Run();
    Simulator::Destroy();

    // Test case 3, some packets are ECN capable, with CE threshold set to 2ms
    queue = CreateObject<CoDelQueueDisc>();
    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("UseEcn", BooleanValue(true)),
                          true,
                          "Verify that we can actually set the attribute UseEcn");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("CeThreshold", TimeValue(MilliSeconds(2))),
                          true,
                          "Verify that we can actually set the attribute CeThreshold");

    queue->Initialize();

    // First 3 packets in the queue are ecnCapable
    Enqueue(queue, pktSize, 3, true);
    // Rest of the packet are not ecnCapable
    Enqueue(queue, pktSize, 17, false);
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          20 * modeSize,
                          "There should be 20 packets in queue.");

    // Although the first dequeue occurs with a sojourn time above target
    // there should not be any target exceeded marked packets in this interval
    Simulator::Schedule(waitUntilFirstDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        3);

    // This dequeue should cause a packet to be marked
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        3);

    // Although we are in dropping state, it's not time for next packet to be target exceeded marked
    // the dequeue should not cause a packet to be target exceeded marked
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        3);

    // In dropping time and it's time for next packet to be dropped as packets are not ECN capable
    // the dequeue should cause packet to be dropped
    Simulator::Schedule(waitUntilSecondDequeue * 2,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        3);

    Simulator::Run();
    Simulator::Destroy();

    // Test case 4, queue with ECN capable traffic and CeThreshold set for marking of packets
    // instead of dropping
    queue = CreateObject<CoDelQueueDisc>();
    NS_TEST_ASSERT_MSG_EQ(
        queue->SetAttributeFailSafe("MaxSize", QueueSizeValue(QueueSize(m_mode, modeSize * 500))),
        true,
        "Verify that we can actually set the attribute MaxSize");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("UseEcn", BooleanValue(true)),
                          true,
                          "Verify that we can actually set the attribute UseEcn");
    NS_TEST_ASSERT_MSG_EQ(queue->SetAttributeFailSafe("CeThreshold", TimeValue(MilliSeconds(2))),
                          true,
                          "Verify that we can actually set the attribute CeThreshold");

    queue->Initialize();

    // ECN capable traffic to induce packets to be marked
    Enqueue(queue, pktSize, 20, true);
    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                          20 * modeSize,
                          "There should be 20 packets in queue.");

    // The first dequeue occurs with a sojourn time below CE threshold
    // there should not any be CE threshold exceeded marked packets
    Simulator::Schedule(MilliSeconds(1),
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        4);

    // Sojourn time above CE threshold so this dequeue should cause a packet to be CE thershold
    // exceeded marked
    Simulator::Schedule(MilliSeconds(3),
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        4);

    // the dequeue should cause a packet to be CE threshold exceeded marked
    Simulator::Schedule(waitUntilFirstDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        4);

    // In dropping time and it's time for next packet to be dropped but because of using ECN, packet
    // should be marked
    Simulator::Schedule(waitUntilSecondDequeue,
                        &CoDelQueueDiscBasicMark::Dequeue,
                        this,
                        queue,
                        modeSize,
                        4);

    Simulator::Run();
    Simulator::Destroy();
}

void
CoDelQueueDiscBasicMark::Enqueue(Ptr<CoDelQueueDisc> queue,
                                 uint32_t size,
                                 uint32_t nPkt,
                                 bool ecnCapable)
{
    Address dest;
    for (uint32_t i = 0; i < nPkt; i++)
    {
        queue->Enqueue(Create<CodelQueueDiscTestItem>(Create<Packet>(size), dest, ecnCapable));
    }
}

void
CoDelQueueDiscBasicMark::Dequeue(Ptr<CoDelQueueDisc> queue, uint32_t modeSize, uint32_t testCase)
{
    uint32_t initialTargetMarkCount =
        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
    uint32_t initialCeThreshMarkCount =
        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
    uint32_t initialQSize = queue->GetCurrentSize().GetValue();
    uint32_t initialDropNext = queue->GetDropNext();
    Time currentTime = Simulator::Now();
    uint32_t currentDropCount = 0;
    uint32_t currentTargetMarkCount = 0;
    uint32_t currentCeThreshMarkCount = 0;

    if (initialTargetMarkCount > 0 && currentTime.GetMicroSeconds() >= initialDropNext &&
        testCase == 3)
    {
        queue->TraceConnectWithoutContext(
            "DropNext",
            MakeCallback(&CoDelQueueDiscBasicMark::DropNextTracer, this));
    }

    if (initialQSize != 0)
    {
        Ptr<QueueDiscItem> item = queue->Dequeue();
        if (testCase == 1)
        {
            currentDropCount =
                queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
            if (currentDropCount == 1)
            {
                nPacketsBeforeFirstDrop = initialQSize;
            }
        }
        else if (testCase == 2)
        {
            if (initialTargetMarkCount == 0 && currentTime > queue->GetTarget())
            {
                if (currentTime < queue->GetInterval())
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be 1 packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentTargetMarkCount,
                        0,
                        "We are not in dropping state."
                        "Sojourn time has just gone above target from below."
                        "Hence, there should be no target exceeded marked packets");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        0,
                        "Marking due to CE threshold is disabled"
                        "Hence, there should not be any CE threshold exceeded marked packet");
                }
                else if (currentTime >= queue->GetInterval())
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    nPacketsBeforeFirstMark = initialQSize;
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(
                        queue->GetCurrentSize().GetValue(),
                        initialQSize - modeSize,
                        "Sojourn time has been above target for at least interval."
                        "We enter the dropping state and perform initial packet marking"
                        "So there should be only 1 more packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentTargetMarkCount,
                                          1,
                                          "There should be 1 target exceeded marked packet");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        0,
                        "There should not be any CE threshold exceeded marked packet");
                }
            }
            else if (initialTargetMarkCount > 0)
            { // In dropping state
                if (currentTime.GetMicroSeconds() < initialDropNext)
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "We are in dropping state."
                                          "Sojourn is still above target."
                                          "However, it's not time for next target exceeded mark."
                                          "So there should be only 1 more packet dequeued");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentTargetMarkCount,
                                          1,
                                          "There should still be only 1 target exceeded marked "
                                          "packet from the last dequeue");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        0,
                        "There should not be any CE threshold exceeded marked packet");
                }
                else if (currentTime.GetMicroSeconds() >= initialDropNext)
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "We are in dropping state."
                                          "It's time for packet to be marked"
                                          "So there should be only 1 more packet dequeued");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentTargetMarkCount,
                                          2,
                                          "There should 2 target exceeded marked packet");
                    NS_TEST_ASSERT_MSG_EQ(
                        nPacketsBeforeFirstDrop,
                        nPacketsBeforeFirstMark,
                        "Number of packets in the queue before drop should be equal"
                        "to number of packets in the queue before first mark as the behavior "
                        "until packet N should be the same.");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        0,
                        "There should not be any CE threshold exceeded marked packet");
                }
            }
        }
        else if (testCase == 3)
        {
            if (initialTargetMarkCount == 0 && currentTime > queue->GetTarget())
            {
                if (currentTime < queue->GetInterval())
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be 1 packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentTargetMarkCount,
                        0,
                        "We are not in dropping state."
                        "Sojourn time has just gone above target from below."
                        "Hence, there should be no target exceeded marked packets");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        1,
                        "Sojourn time has gone above CE threshold."
                        "Hence, there should be 1 CE threshold exceeded marked packet");
                }
                else if (currentTime >= queue->GetInterval())
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(
                        queue->GetCurrentSize().GetValue(),
                        initialQSize - modeSize,
                        "Sojourn time has been above target for at least interval."
                        "We enter the dropping state and perform initial packet marking"
                        "So there should be only 1 more packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentTargetMarkCount,
                                          1,
                                          "There should be 1 target exceeded marked packet");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          1,
                                          "There should be 1 CE threshold exceeded marked packets");
                }
            }
            else if (initialTargetMarkCount > 0)
            { // In dropping state
                if (currentTime.GetMicroSeconds() < initialDropNext)
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "We are in dropping state."
                                          "Sojourn is still above target."
                                          "However, it's not time for next target exceeded mark."
                                          "So there should be only 1 more packet dequeued");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentTargetMarkCount,
                                          1,
                                          "There should still be only 1 target exceeded marked "
                                          "packet from the last dequeue");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          2,
                                          "There should be 2 CE threshold exceeded marked packets");
                }
                else if (currentTime.GetMicroSeconds() >= initialDropNext)
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentTargetMarkCount =
                        queue->GetStats().GetNMarkedPackets(CoDelQueueDisc::TARGET_EXCEEDED_MARK);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(
                        queue->GetCurrentSize().GetValue(),
                        initialQSize - (m_dropNextCount + 1) * modeSize,
                        "We are in dropping state."
                        "It's time for packet to be dropped as packets are not ecnCapable"
                        "The number of packets dequeued equals to the number of times m_dropNext "
                        "is updated plus initial dequeue");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentDropCount,
                        m_dropNextCount,
                        "The number of drops equals to the number of times m_dropNext is updated");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentTargetMarkCount,
                        1,
                        "There should still be only 1 target exceeded marked packet");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          2,
                                          "There should still be 2 CE threshold exceeded marked "
                                          "packet as packets are not ecnCapable");
                }
            }
        }
        else if (testCase == 4)
        {
            if (currentTime < queue->GetTarget())
            {
                if (initialCeThreshMarkCount == 0 && currentTime < MilliSeconds(2))
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be 1 packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(
                        currentCeThreshMarkCount,
                        0,
                        "Sojourn time has not gone above CE threshold."
                        "Hence, there should not be any CE threshold exceeded marked packet");
                }
                else
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be only 1 more packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          1,
                                          "Sojourn time has gone above CE threshold."
                                          "There should be 1 CE threshold exceeded marked packet");
                }
            }
            else if (initialCeThreshMarkCount > 0 && currentTime < queue->GetInterval())
            {
                if (initialCeThreshMarkCount < 2)
                {
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be only 1 more packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          2,
                                          "There should be 2 CE threshold exceeded marked packets");
                }
                else
                { // In dropping state
                    currentDropCount =
                        queue->GetStats().GetNDroppedPackets(CoDelQueueDisc::TARGET_EXCEEDED_DROP);
                    currentCeThreshMarkCount = queue->GetStats().GetNMarkedPackets(
                        CoDelQueueDisc::CE_THRESHOLD_EXCEEDED_MARK);
                    NS_TEST_ASSERT_MSG_EQ(queue->GetCurrentSize().GetValue(),
                                          initialQSize - modeSize,
                                          "There should be only 1 more packet dequeued.");
                    NS_TEST_ASSERT_MSG_EQ(currentDropCount,
                                          0,
                                          "There should not be any packet drops");
                    NS_TEST_ASSERT_MSG_EQ(currentCeThreshMarkCount,
                                          3,
                                          "There should be 3 CE threshold exceeded marked packet");
                }
            }
        }
    }
}

/**
 * \ingroup traffic-control-test
 *
 * \brief CoDel Queue Disc Test Suite
 */
static class CoDelQueueDiscTestSuite : public TestSuite
{
  public:
    CoDelQueueDiscTestSuite()
        : TestSuite("codel-queue-disc", UNIT)
    {
        // Test 1: simple enqueue/dequeue with no drops
        AddTestCase(new CoDelQueueDiscBasicEnqueueDequeue(QueueSizeUnit::PACKETS), TestCase::QUICK);
        AddTestCase(new CoDelQueueDiscBasicEnqueueDequeue(QueueSizeUnit::BYTES), TestCase::QUICK);
        // Test 2: enqueue with drops due to queue overflow
        AddTestCase(new CoDelQueueDiscBasicOverflow(QueueSizeUnit::PACKETS), TestCase::QUICK);
        AddTestCase(new CoDelQueueDiscBasicOverflow(QueueSizeUnit::BYTES), TestCase::QUICK);
        // Test 3: test NewtonStep() against explicit port of Linux implementation
        AddTestCase(new CoDelQueueDiscNewtonStepTest(), TestCase::QUICK);
        // Test 4: test ControlLaw() against explicit port of Linux implementation
        AddTestCase(new CoDelQueueDiscControlLawTest(), TestCase::QUICK);
        // Test 5: enqueue/dequeue with drops according to CoDel algorithm
        AddTestCase(new CoDelQueueDiscBasicDrop(QueueSizeUnit::PACKETS), TestCase::QUICK);
        AddTestCase(new CoDelQueueDiscBasicDrop(QueueSizeUnit::BYTES), TestCase::QUICK);
        // Test 6: enqueue/dequeue with marks according to CoDel algorithm
        AddTestCase(new CoDelQueueDiscBasicMark(QueueSizeUnit::PACKETS), TestCase::QUICK);
        AddTestCase(new CoDelQueueDiscBasicMark(QueueSizeUnit::BYTES), TestCase::QUICK);
    }
} g_coDelQueueTestSuite; ///< the test suite
